EFFECT OF MULTISTEP WAFER-ANNEALING ON MAIN TRAPS IN CZOCHRALSKI-GROWN SEMIINSULATING GAAS

Both multistep wafer-annealed (MWA) and ingot-annealed semi-insulating (SI) GaAs wafers, grown by the Czochralski technique, are characteriz ed by using normalized thermally stimulated current (NTSC) spectroscop y. Two main NTSC traps, T-3 at 200 K and T-5 at 140 K, which are thoug ht to be related to arsenic vacancy defects, are found to be largely s uppressed by MWA processes, especially by a new MWA process. Concomita nt with a decrease of these traps, a significant increase of the thres hold electrical field for both the thermal quenching of T-5 and the lo w-temperature photocurrent saturation has been observed. (C) 1996 Amer ican Institute of Physics.